1. Field of the Invention
This application relates generally to heating and cooling apparatus, and more particularly to a heating and cooling system having a heat transfer mechanism.
2. Description of Related Art
With the steadily increasing costs of fossil and other depletable types of fuels, which are presently being used to obtain desirable temperature levels in environmental and process loads, greater emphasis is being directed toward developing systems and methods to extract energy from the vast, virtually unlimited thermal energy stored in the earth and transferring that energy to loads for heating purposes and, reversely, extracting thermal energy from the loads and transferring that energy to the earth for dissipation therein for cooling purposes. One type of previous mechanism for accomplishing such heat exchange objectives is commonly referred to as a heat pump.
Conventional air-source reverse-cycle heat pump systems are commonly used for providing heating and/or cooling to building environmental spaces, manufacturing processes, and a variety of other uses. Properly used, such systems can be quite effective in environments where the ambient temperature is not extreme. Although generally acceptable performance is obtained in such moderate ambient temperature conditions, such systems leave a lot to be desired during extreme fluctuations in ambient temperatures, wherein substantial reductions in heating and cooling capabilities and in operating efficiencies are seen.
In recent years, heat-pump systems have been developed which use ground-source heat exchangers whereby the earth is utilized as a heat source and/or sink, as appropriate. Heat-pump systems utilizing the more moderate temperature range of the earth provide efficiencies which are substantially improved over those obtained from air-source heat pump systems. Such earth exchange systems are based on the concept that useful thermal energy could be transferred to and from the earth by the use of subterranean tubes in flow communication with various above ground components.
In a direct exchange ground loop system, refrigerant coolant pumped through such tubes by a compressor serves as a carrier to convey thermal energy absorbed from the earth, as a heat source, to the above ground components for further distribution as desired for heating purposes. Similarly, the coolant carries thermal energy from the above ground components through the subterranean tubes for dissipation of heat energy into the earth, as a heat sink, for cooling purposes.
Unfortunately, a number of major complications may arise when refrigerant is pumped through the subterranean tubes. First, lubricant oil which characteristically escapes from the compressor while the system is operating is carried along with the refrigerant throughout the system and tends to accumulate in the tubes, substantially reducing the ability of the subterranean tubes to perform their originally intended function. Second, when an energy demand cycle is completed, the system would shut down while waiting for a subsequent demand for energy transfer. As a result, a certain amount of liquid refrigerant then passing through the subterranean tubes would lose its momentum and revert to liquid, leading to low pressure fault conditions. A third problem, which was generally observed for prior art heat pumps, was the absence of a mechanism for achieving refrigerant pressure equalization subsequent to system shutdown for reducing start-up loads. Because of the absence of such pressure equalization, the service life of the compressor was reduced.
Previous attempts to circumvent some of the aforesaid problems generally followed either of two approaches: (i) using a vertically disposed, single-closed loop, subterranean exchanger, or (ii) using a plurality of closed loop systems working in combination, with one of such loops horizontally or vertically disposed subterraneously.
According to Amerman et al in U.S. Pat. No. 6,585,036. “Several companies in the past have produced “energy meters” that calculate and record energy extracted from a circulating water loop and bill the customer for the energy used. This has been done for many years in “district heating” applications in Europe. Such equipment only records heat flow in one direction—usually heat extracted from the flow stream, not heat rejected into the flow stream as would be the case in a heat pump in a cooling mode (air conditioning operation)”. Further, Amerman et al. in U.S. Pat. No. 6,585,036 extended such metering to direct exchange ground loop systems by incorporating measurement devices directly in the heat pump's flow. Such direct exchange loops, however, are not practical for complex installations because temperature gradients in various elements of the system can lead to vapor locks or condensation within the loop, as previously discussed.
The concept of individual unit monitoring with individually tailored systems is shown for a hot air system in U.S. Pat. No. 4,049,044 wherein each separate blower unit that distributes the conditioned air throughout the individual units is coupled to drive a related integrating means to produce a readout in accordance with the fan usage. For example, in Europe, heat responsive metering units which are hung directly on the heat exchanges are widely employed for monitoring and recording of the actual energy usage based on the hot water flowing through a radiator. Such systems are widely accepted, with various countries providing legal regulation of their usage. Generally, it has been found that the residents' incentive is such as to substantially reduce their usage of energy and studies have indicated that the reduction may be on the order of 30%. The current focus on reducing energy usage and corresponding carbon emissions thus indicates that individual metering of energy consumption in multiple unit complexes is a highly desirable social factor as well as an advantage to the individual residents to insure that they are being burdened with only those costs related to their actual consumption. Both the invention disclosed in U.S. Pat. No. 4,049,044 and the radiator systems of Europe, however, depend on measuring heat output, as opposed to measuring energy input. Measuring only heat output does not allow for accurate measurement of each energy input, such as electricity from the local utility and thermal energy from the ground loop and thus cannot be used to effectively allocate costs.
Marathe et. al. in U.S. Pat. No. 4,306,293 attempted to address this issue by measuring the flow rate from the energy source and inferring the energy flow to individual units. Through pre-programmed weightings this approach could compensate for variations in flow rates through different loads, but such one-time weighting, factors are subject to changes in specific conditions over time. In addition, each embodiment relied on a pre-determined system configuration that did not vary. There was no flexibility for growth or change to the system over time nor dynamic adjustment of the pumping source to changing load patterns, leading to inefficiencies since no means are provided to vary the pumping rate depending on load. These limitations reduce efficiency through improper pumping pressures and lead to a loss of accuracy, particularly over time as actual conditions drift from initial system weighting calculations. Low accuracy prevents such systems from being reliably used in situations where accuracy is important, such as allocation of costs to individual loads, as may be found in multi-unit residential and commercial buildings.
Another attempt was made in U.S. Pat. No. 5,992,507 by Peterson, et. al, to manage a plurality of heating loads, but this system required a purging manhole in direct fluid communication with the input and output loop manifolds as well as an external pumping mechanism within each thermal load. Both of these requirements add significantly to system installation costs and impose additional costly requirements on each thermal load serviced by the system.
Despite improvements, a further disadvantage arising from prolonged usage of the earth-source heat-pump systems still remained: stressing of the earth's ability to transfer and/or store large quantities of thermal energy in the vicinity of the heat exchanger for extended periods of time. This situation was generally particularly noticeable for systems used for manufacturing processes or under-sized environmental space conditioning applications. A similar situation could also be seen in climates imbalanced in their annual heating or cooling needs, such as northern climates requiring substantially more heating than cooling over the course of a year or southern climates requiring the opposite.
An attempted solution to the stressing problem included the augmentation of a liquid-source heat pump with a liquid-heat exchanger loop which integrated both a liquid-based subterranean heat exchanger and a liquid-based fan coil in an attempt to boost the performance of the liquid-source heat pump, such as that taught by Margen in U.S. Pat. No. 4,091,636. In that system, only one or the other of the heat exchangers were operated at any one time. Unfortunately, such integrated systems generally failed to realize optimum operational efficiencies. Further, the integrated refrigerant and liquid subsystems produced a system with substantially increased complexity and maintenance requirements.
In another approach, such as that taught by Gazes et al. in U.S. Pat. No. 4,920,757, a third fan coil was integrated with a refrigerant-based subterranean heat pump design. That system, however, did not employ the additional fan coil as an alternative energy source. Instead, it merely used the coil to control excess refrigerant build-up in the subterranean heat exchanger; during one cycle, it worked serially with the indoor-heat exchanger and, during the other cycle, it worked serially with the subterranean heat exchanger.
In yet another approach, as taught by Tressler in U.S. Pat. No. 5,239,838, two separate heat exchange sources were incorporated into a single heat pump system. That system could either be operated as an air-source heat pump or as a liquid-source heat pump attached to a thermal storage tank, which was in turn heated by a water heater or solar panel. The system was designed to perform as an air-source heat pump or, during the heating cycle, to draw thermal energy from the storage tank. Again, that system did not realize optimum operational efficiencies because it did not coordinate concurrent utilization of both energy sources.
In still another approach, as taught by Blackshaw et al. in U.S. Pat. No. 4,646,538, a system incorporated three heat exchangers: a secondary liquid-based subterranean heat exchanger, an indoor fan coil heat exchanger, and a hot-liquid heat exchanger. Although the system could transfer heat between any two of the heat exchangers, the Blackshaw et al. system did not utilize the third heat exchanger to augment the performance of the subterranean heat exchange loop and optimum efficiencies were not fully realized.
In yet another combination, as taught by Dressler et al. in U.S. Pat. No. 5,461,876, a system provided a combination of a refrigerant-based subterranean heat exchanger in combination with an ambient-air exchanger. Although the system may boost efficiency in certain environmental conditions, it was still limited to an efficiency that essentially averaged the contribution of each source depending on existent ambient conditions.
Finally, Johnson and Tinkler in U.S. Pat. No. 6,694,766 showed a means of capturing waste heat or excess cooling capacity from an existing process but again did nothing to capture the benefit of additional heat source or sink gains that could be available through supplemental thermal systems.
What is required is an affordable mechanism of providing a comprehensive view of system performance. It is therefore an object of the present invention to provide a pumping and measurement system which modularly grows system capacity by adding additional pumping power with each additional load system, as well as directly measuring energy flowing through the module, providing a more accurate measure of energy consumed or produced. Higher accuracy allows for reliable cost allocation, particularly in multi-unit commercial and residential buildings. Furthermore, detailed visibility of system performance allows for substantial gains in efficiency by incorporating non-ambient heat sources/sinks as may be desirable to enhance performance. Higher efficiency further allows system designers and installers to reduce the heat transfer demand of the ground loop, reducing the still substantial cost of trenching, drilling or otherwise installing the earth heat transfer system.
The present invention and the various embodiments described and envisioned herein provides a modular geothermal measurement system that provides for the pumping of a heat transfer fluid and that simplifies on-site installation time, allows for growth of the system over time, increases ground loop pumping power while providing energy transfer data specific to each thermal load, and allows the beneficiary of a geothermal investment to be billed for their benefit, enabling the investor to capture the economic benefit of the investment.
It is, therefore, an object of at least certain embodiments of the present invention to provide new, useful, unique, efficient, nonobvious systems and methods for providing energy to an end user from a ground energy transfer system and, in one aspect, from an energy transfer loop system. Such systems and methods include metering and quantifying energy delivery for use in various later calculations and transactions. Such systems and methods further include measuring energy transfer for each of a variety of heating or cooling loads for use in later calculations and transactions. It is another object of the present invention to provide new, useful, unique, efficient, nonobvious systems and methods for combining heating and cooling sources to improve overall system performance. It is another object of the present invention to provide new systems and methods for measuring Carbon Dioxide reduction to communicate the social or economic benefits of such reduction.